Organic light-emitting diode (OLED) display is a kind of all solid state active display. OLED displays are regarded as newly emerging next-generation displays due to the characteristics such as high brightness, high contrast, ultrathin and ultralight profile, low power consumption, no limitation of visual angle, wide working temperature range, etc. One of the problems that OLED display technology faces until today is afterimage display.
When a display has being display the same image for a long time, after the process of switching the currently displayed image into a next image, the currently displayed image will be partially retained in the next image. This phenomenon is referred to as afterimage (screen burn-in). The afterimage phenomenon of an OLED display is relevant to the drift of the threshold voltage (Vth) for driving thin-film transistors (TFTs) of OLED pixels. In different display periods, different display grayscales will produce different TFT drain currents, so the drift of the TFT threshold voltage (Vth) of the OLED pixels may be caused in different degrees.
For instance, FIG. 1A is a schematic diagram of an image 1 that is displayed by the display; FIG. 1B is a schematic diagram of an image 2 that is required to be displayed by the display; and FIG. 1C is a schematic diagram of the image 2 actually displayed by the display. After the display has being display the image 1, e.g., a black and white checkerboard image, for a long time, when the image displayed by the display is switched into a new image 2, e.g., an image with the grayscale of 127 as illustrated in FIG. 1B, the checkerboard image of the image 1 as illustrated in FIG. 1A is still partially retained as illustrated in FIG. 1C.
When the display loads and displays one image continuously for a long time, afterimage may be caused. In the case of slight afterimage, generally the afterimage gradually fades away. But if a still image is displayed for too long time or accumulated in a long term, the afterimage phenomenon becomes very severe, so the afterimage will result in permanent and irreversible damage to the display.